CUDIMM and CSODIMM

[stanlawj]

What is CUDIMM?

https://www.kingston.com/en/blog/system-builder/what-is-a-cudimm-csodimm

As DDR5 standard speeds get faster and faster for next-generation desktop and laptop computers, stability and data integrity become critical issues to mitigate. Increasing speeds means electronic noise and jitter become problematic, potentially resulting in errors, lost data or system freezes.

To address this challenge, the body for maintaining industry standards in memory, JEDEC, specified a new requirement in late 2023 for DDR5 Unbuffered DIMMs (Dual Inline Memory Module) and DDR5 SODIMMs (Small Outline Dual Inline Memory Module).

Beginning with the introduction of 6400MT/s DDR5, a Client Clock Driver (CKD) component must be added to the memory module to redrive the clock signal, which minimises noise and jitter and improves overall signal integrity.

New memory classification​

To differentiate from legacy DDR5 modules that don’t feature a clock driver, JEDEC requires the addition of a “C” for “Clocked” to indicate the inclusion of this component, hence the new module types CUDIMM and CSODIMM. This is an important distinction, since CUDIMMs and CSODIMMs use the same sockets as existing DDR5 UDIMMs and SODIMMs. To prevent compatibility issues, the chipset and motherboard manufacturers will roll out BIOS updates to legacy motherboards that disable the clock driver if a CUDIMM/CSODIMM is installed. When a CUDIMM or CSODIMM is installed on a legacy system, it will automatically operate at the supported speed of that chipset and processor.

 

[stanlawj]

Conclusion: Beginning with 2025, CUDIMM/CSODIMM replace UDIMM/SODIMM.

As of now, dual-channel CUDIMM kits are available up to a max capacity of 48GB (2x24GB) are available.

G.Skill Trident Z5 CK series
Teamgroup T-Force Xtreem CKD
V-Color Manta Xfinity RGB CKD
Kingston FURY Renegade DDR5
Crucial DDR5 Pro CUDIMM/CSODIMM
Patriot Memory Signature Line DDR5 CKD

I'm not aware if any of these CUDIMMs are available for purchase locally yet.

 

[stanlawj]

Next question, what about CAMM vs CUDIMM/CSODIMM?

CAMM is a form-factor spec, unlike the clock-driver which is an electrical spec. It compacts the size and shortens the signal traces to enable higher clocks as well.
Maybe CAMM with clock driver will enable >10,000 MT/s DDR5 in the future for laptop and Mini PCs?

https://www.kingston.com/en/blog/system-builder/what-is-camm

CAMM stands for Compression Attached Memory Module and is a new memory module form factor designed for thin-profile laptops or all-in-one systems. Initially a Dell proprietary design, in late 2022 the CAMM concept was introduced by Dell to JEDEC, the industry standards body for memory modules, to create a new standard for anyone to use.

Initial designs for the industry-standard CAMM, called CAMM2, were made available in late 2023 for computer and memory module manufacturers to adopt, with additional designs in development slated for release by the second half of 2024. The challenge to any new memory design is always standardisation and adoption by the industry, particularly chipset architects (Intel, AMD). Dell’s investment and willingness to share their design royalty-free with the JEDEC standards body is a testament to their commitment to standardisation.

Instead of leads on the bottom edge of the conventional memory module that plug into a socket, the CAMM uses a compression connector that mounts to a thin interposer on the motherboard. Screws are then used to secure the CAMM in place. A CAMM can be single sided to reduce z-height to accommodate a very thin profile system, with options for the width and length of the CAMM module to support higher memory capacities. The JEDEC CAMM2 designs support different types of memory components (DDR5 and LPDDR5/X), which provide flexibility for manufacturers to choose the right memory type for their systems.

Advantages engineered into the CAMM2 designs are support for higher capacities not available with SODIMMs, such as 128GB on a single module and support for dual memory channels. Traditionally it would require two SODIMMs to complete a dual-channel configuration. With selected CAMM2 designs, both channels are featured on one module, allowing for double the aggregated memory bandwidth in one socket.

As an approved memory supplier to Dell, Kingston is well positioned to support the CAMM revolution, with investment and infrastructure to manufacture and test this new form factor already in place. Keep an eye on the Kingston website for our CAMM2 solutions to appear in the second half of 2024.

 

[KYZT2021]

adoption rate not high

 

[stanlawj]

adoption rate not high

CUDIMM will enable high-speed high-capacity DDR5 DIMMS.

The magic is getting 128GB (2x64GB or 4x32GB) at DDR5-8000 (= 128GB/s theoretical bandwidth)

 

[fkchon]

CUDIMM has an external clock generator inside the ram module itself that allows it to run at even higher frequency and be less reliant on the IMC inside the CPU.
This is backwards compatible with DDR5 and I have seen despite AM5 not yet supporting CUDIMM, it is able to get higher clocks (probably because its also much better binned). Right now its only working on Arrow Lake chips.

CAMM is what you want, it has a shorter path and more solid trace that will give you higher quality electrical signal to the CPU. Dont think this is on market yet.

 

[1 Ghz]

CUDIMM has an external clock generator inside the ram module itself that allows it to run at even higher frequency and be less reliant on the IMC inside the CPU.
This is backwards compatible with DDR5 and I have seen despite AM5 not yet supporting CUDIMM, it is able to get higher clocks (probably because its also much better binned). Right now its only working on Arrow Lake chips.

CAMM is what you want, it has a shorter path and more solid trace that will give you higher quality electrical signal to the CPU. Dont think this is on market yet.

CUDIMM is backwards compatible with conventional DDR5 via bypass mode, but it might not be a drop-in replacement.

Eg. Ryzen 7000 doesn't work with CUDIMM, but that's not an issue with Ryzen 8000/9000, even though both share the same socket.

 

[fkchon]

CUDIMM is backwards compatible with conventional DDR5 via bypass mode, but it might not be a drop-in replacement.

Eg. Ryzen 7000 doesn't work with CUDIMM, but that's not an issue with Ryzen 8000/9000, even though both share the same socket.

Oh had no idea it didn't work on 7000 series, I've seen people post 9000 series with CUDIMM so I just assumed it worked as well.

 

[stanlawj]

Still no sign of local availability of high-speed CUDIMMs.

 

[fkchon]

Apparently MSI X870 boards can use CUDIMM on Ryzen 9000 series.

 

[stanlawj]

G.Skill launches DDR5 CSODIMM.

https://wccftech.com/g-skill-cso-dimm-ddr5-memory-overclockable-up-to-8133-mtps/

8133 MT/s in 2x24 GB configuration with a latency of CL46-52-52-130